It is estimated that the combined value of all business-based COBOL applications running on mainframes is in excess of a trillion US dollars. Some estimates indicate that there are nearly 180 billion lines of COBOL code in use around the world. The cost of maintaining these legacy applications is increasing and organizations are having difficulty in obtaining trained people, as the code continues to be outdated.
One solution is to migrate these applications from mainframes to a newer and cheaper maintenance systems based on Microsoft Windows® or Linux®. Such migration is called “re-hosting” of legacy applications. Similarly, due to the end of mainstream support for Visual Basic 6 (VB), organizations have started migrating VB applications to VB.net, which further increases the scope of re-hosting of applications. It is estimated that billions of dollars will be spent on re-hosting of such legacy applications in the coming years.
To facilitate successful re-hosting and migration, tools have been developed that automatically port COBOL source code running on mainframes onto the new systems, specifically Microsoft Windows® based systems. Micro Focus Studio® is one such tool that re-hosts COBOL applications running on mainframes to Microsoft Windows® without adding new code or changing existing code manually.
For proper migration, the re-hosted applications need to be verified for its original functionality on the new systems. To ascertain the accuracy of the original functionality, organizations perform system testing of re-hosted applications in new environments using functional test cases. However, being legacy applications, in many instances test cases are not available in any form. Further, due to non-availability of software requirements specifications or design artifacts for these legacy applications, the existing automatic test case generation techniques based on such artifacts cannot be used. Therefore, testers are facing challenges to test the re-hosted applications on new platforms.
In practice, the test designers create functional test cases or scenarios based on their own understanding of the system functionality. Once these test cases are executed successfully, it is assumed that the re-hosting or migration is successful. This process of verification is labor intensive and also prone to errors because some functionalities might have been missed, leaving some parts of the application untested.